For example, as disclosed in Japanese Laid-Open Patent Publication No. H10-055712, a planar light source device incorporated into a liquid crystal display apparatus is equipped with a light guide plate.
As the material of the light guide plate, polymethyl methacrylate (hereinafter, referred to as PMMA) has been hitherto used. However, replacing PMMA with a polycarbonate resin has proceeded since the polycarbonate resin has high heat resistance and high mechanical strength.
The polycarbonate resin is superior to PMMA in mechanical properties, thermal properties, and electrical properties but slightly inferior to PMMA in light transmittance. Therefore, there is a problem that a planar light source device using a light guide plate made of a polycarbonate resin has a lower brightness than one using a light guide plate made of PMMA.
Accordingly, for example, as disclosed in Patent Literature 2 to 6, various resin compositions each including a polycarbonate resin and another material have been proposed in order to obtain a light transmittance equal to or higher than that of PMMA to improve the brightness of a light guide plate.
However, the resin compositions disclosed in Japanese Laid-Open Patent Publication No. H09-020860, Japanese Laid-Open Patent Publication No. H11-158364, Japanese Laid-Open Patent Publication No. 2001-215336, Japanese Laid-Open Patent Publication No. 2004-051700, and International Publication WO 2011/083635 cannot fully meet the requirements as the material for recent light guide plates.